As an imaging technique capable of obtaining a distance in the depth direction from two-dimensional array information, a technique using a reference ray, a stereo distance measuring technique using a plurality of cameras, and so on are known. In recent years, needs for such techniques are increasing as new input devices in the use of public welfare.
As an imaging scheme capable of obtaining the distance without using a reference ray in order to hold down the cost, there is a scheme using that a ray angle from a subject via an image formation lens contains distance information as the principle of the distance measurement. For example, a structure in which an image formation microlens array (MLA) is disposed over pixels and an aperture for dividing the ray is disposed on the object side of each image formation microlens has been proposed. Each image formation microlens acquires an image having a peak in intensity distribution according to a distance to the subject by re-imaging an image imaged by an image formation lens from each position. The distance to the subject can be estimated by measuring the number of signal peaks.